Network Device Relating to Digital Subscriber Line

1. A network device, comprising: a communication port; a system-on-a-chip (SoC), operated under a first DC operation voltage and a second DC operation voltage, wherein the SoC is used for generating a dying gasp signal when the network device runs out of power; a line driver, coupled between the communication port and the SoC, and operated under the second DC operation voltage and a third DC operation voltage, wherein the line driver is used for receiving and amplifying the dying gasp signal from the SoC, and transmitting the amplified dying gasp signal to a central office (CO); a first conversion unit, coupled to the SoC and the line driver, for receiving and converting a DC input voltage, so as to generate the first DC operation voltage and the second DC operation voltage; a second conversion unit, coupled to the line driver, for receiving and converting the DC input voltage, so as to generate the third DC operation voltage; a first energy-storage unit, coupled to the first conversion unit, for providing a first DC power relating to the DC input voltage to the first conversion unit when the network device runs out of power; and a second energy-storage unit, coupled to the second conversion unit, for providing a second DC power relating to the DC input voltage to the second conversion unit when the network device runs out of power.

2. The network device according to claim 1 , wherein the SoC comprises: a processing part, for being served as core of operation of the network device; a detection part, for detecting whether the network runs out of power or not; and a dying gasp signal generating part, for generating the dying gasp signal when the network device runs out of power.

3. The network device according to claim 1 , wherein the first conversion unit comprises: a first DC-DC converter, for receiving and converting the DC input voltage, so as to generate the first DC operation voltage; and a second DC-DC converter, for receiving and converting the DC input voltage, so as to generate the second DC operation voltage.

4. The network device according to claim 1 , wherein the second conversion unit comprises: a DC-DC converter, for receiving and converting the DC input voltage, so as to generate the third DC operation voltage.

5. The network device according to claim 1 , wherein the first energy-storage unit comprises: an energy-storage element, for providing the first DC power to the first conversion unit when the network device runs out of power, otherwise, for being charged in response to the DC input voltage.

6. The network device according to claim 5 , wherein the first energy-storage unit further comprises: a diode, having an anode coupled to the energy-storage element and a cathode coupled to the first conversion unit; and a resistor, coupled with the diode in parallel.

7. The network device according to claim 5 , wherein the energy-storage element comprises at least a capacitor.

8. The network device according to claim 1 , wherein the second energy-storage unit comprises: an energy-storage element, for providing the first DC power to the second conversion unit when the network device runs out of power, otherwise, for being charged in response to the DC input voltage.

9. The network device according to claim 8 , wherein the second energy-storage unit further comprises: a diode, having an anode coupled to the energy-storage element and a cathode coupled to the second conversion unit; and a resistor, coupled with the diode in parallel.

10. The network device according to claim 8 , wherein the energy-storage element comprises at least a capacitor.

11. The network device according to claim 1 , further comprising: a first diode, having an anode receiving the DC input voltage and a cathode coupled to the first conversion unit; and a second diode, having an anode receiving the DC input voltage and a cathode coupled to the second conversion unit.

12. The network device according to claim 9 , further comprising: a power conversion unit, for receiving and converting an AC power or a DC power, so as to provide the DC input voltage; a third diode, having an anode receiving the DC input voltage provided by the power conversion unit; a switching unit, coupled to a cathode of the third diode, for transmitting the DC input voltage to the anodes of the first and the second diodes until the network device runs out of power; and an over-voltage-protection (OVP) unit, coupled to the cathode of the third diode and the switching unit, for controlling the switching unit to stop transmitting the DC input voltage when the DC input voltage provided by the power conversion unit is over-voltage.

13. The network device according claim 1 , wherein the network device is a customer's premises equipment (CPE) relating to a digital subscriber line (DSL).

14. The network device according claim 13 , wherein the DSL comprises an asymmetrical DSL (ADSL) or a very high bit rate DSL (VDSL).

15. A network device, comprising: a system-on-a-chip (Soc); a line driver, coupled to the SoC; and at least two independent energy-storage elements, wherein when the network device runs out of power, the SoC generates a dying gasp signal to the line driver in response to energy of one of the energy-storage elements, and then the line driver amplifies and transmits the dying gasp signal to a Central Office (CO) in response to energy of the other of the energy-storage elements.

16. The network device according to claim 15 , wherein the energy-storage elements are capacitors.

17. The network device according claim 15 , wherein the network device is a customer's premises equipment (CPE) relating to a digital subscriber line (DSL).

18. The network device according claim 17 , wherein the DSL comprises an asymmetrical DSL (ADSL) or a very high bit rate DSL (VDSL).